20th January 2021
This refers to the depth of the grooves that run along each tyre. In Australia, the minimum legal tread depth is 1.5mm.
Every tyre has a small bar on its side next to the letters 'TWI'. If the tread is worn down to the level of the TWI, change your tyres.
If you can't find the TWI, place an Aussie 20c coin into the tyre grove. If the tread doesn't reach the bill of the platypus, it's time for fresh rubber.
Look for the placard on the inside of the driver's seat door jamb. It'll tell you the recommended tyre pressures for your car. Check this at least once a month when your tyres are cool, like in the morning before heading out for a drive. A nice, even wear pattern across the tread face means you're doing things right.
The tread will typically 'balloon' in the centre.
You'll see the reverse - more wear on the edges.
Front tyres take more of a beating than rear ones. Rotate your tyres regularly (your local service station can help with that) to spread the load.
If you spot any cuts, bulges or gouges — change those tyres immediately.